diff --git a/addons/mail/mail_thread.py b/addons/mail/mail_thread.py
index 6a32ed3bb52..e676e69552d 100644
--- a/addons/mail/mail_thread.py
+++ b/addons/mail/mail_thread.py
@@ -730,6 +730,9 @@ class mail_thread(osv.AbstractModel):
             else:
                 assert thread_id == 0, "Posting a message without model should be with a null res_id, to create a private message."
                 model_pool = self.pool.get('mail.thread')
+            if not hasattr(hasattr, 'message_post'):
+                context['thread_model'] = model
+                model_pool = self.pool['mail.thread']
             new_msg_id = model_pool.message_post(cr, uid, [thread_id], context=context, subtype='mail.mt_comment', **msg)
 
             if partner_ids:
@@ -1064,7 +1067,7 @@ class mail_thread(osv.AbstractModel):
         model = False
         if thread_id:
             model = context.get('thread_model', self._name) if self._name == 'mail.thread' else self._name
-            if model != self._name:
+            if model != self._name and hasattr(self.pool[model], 'message_post'):
                 del context['thread_model']
                 return self.pool[model].message_post(cr, uid, thread_id, body=body, subject=subject, type=type, subtype=subtype, parent_id=parent_id, attachments=attachments, context=context, content_subtype=content_subtype, **kwargs)
 
diff --git a/addons/mail/wizard/mail_compose_message.py b/addons/mail/wizard/mail_compose_message.py
index 383929a6e07..e3383270548 100644
--- a/addons/mail/wizard/mail_compose_message.py
+++ b/addons/mail/wizard/mail_compose_message.py
@@ -234,6 +234,9 @@ class mail_compose_message(osv.TransientModel):
         for wizard in self.browse(cr, uid, ids, context=context):
             mass_mail_mode = wizard.composition_mode == 'mass_mail'
             active_model_pool = self.pool[wizard.model if wizard.model else 'mail.thread']
+            if not hasattr(active_model_pool, 'message_post'):
+                context['thread_model'] = wizard.model
+                active_model_pool = self.pool['mail.thread']
 
             # wizard works in batch mode: [res_id] or active_ids
             res_ids = active_ids if mass_mail_mode and wizard.model and active_ids else [wizard.res_id]